Re: [linux-dvb] [PATCH] Userspace tuner

Markus Rechberger
2007-09-14T18:59:36Z

On 9/14/07, Alex Deucher <alexdeucher@gmail.com> wrote:
> On 9/14/07, Markus Rechberger <mrechberger@gmail.com> wrote:
> > On 9/14/07, Manu Abraham <abraham.manu@gmail.com> wrote:
> > > Joerg Roedel wrote:
> > > > On Fri, Sep 14, 2007 at 11:57:59AM +0400, Manu Abraham wrote:
> > > >>>>> What do you think about IOMMU?
> > > >>>>>
> > > >>>>>
> > > >>>> Just because AMD or INTEL want to invent some whizzy new technology
> it
> > > >>>> doesn't say anything about the TV card development and retail
> business.
> > > >>>> Intel and AMD have teams of Linux engineers helping operating
> system
> > > >>>> developers bring their ideas and technologies to new platforms.
> That's
> > > a
> > > >>>> million miles away from any of the TV board vendors I know of, who
> have
> > > >>>> little or NO fulltime linux developers and consider the < 5% market
> > > >>>> fringe at best.
> > > >>>>
> > > >>> it helps to virtualize devices and introduces newer features for
> that.
> > > >>> Some interesting projects could be derrived out of that, there are
> > > >>> quite a few interesting papers floating around how drivers could be
> > > >>> handled in future.
> > > >>>
> > > >> IOMMU can be considered similar to the AGP GART, which is similar,
> > > >> remapping the Addresses, as far as i understand.
> > > >
> > > > Common new IOMMUs have only very few in common with the AGP GART. In
> > > > fact, with current modern IOMMU hardware it will be possible to
> > > > implement secure userspace device drivers that are even able to do
> DMA.
> > > > This is not possible with the GART.
> > > >
> > > >> Though you get a physical to virtual translation, what about
> interrupts,
> > > >
> > > > Modern IOMMUs are able to remap interrupts. This will solve the
> problem
> > > > with PCI interrupt sharing.
> > >
> > > What CPU's are we talking about ?
> > >
> >
> > upcoming x86-64 processors from the AMD side. I'm not into what Intel
> > is doing in that area at the moment.
>
> All AMD64 chips have an IOMMU. Only Intel's most recent chips do.
>

It's not available yet, you can read more about it in the following article:

http://developer.amd.com/articlex.jsp?id=101

If you're interested in it I can put together some more information about
it.

Markus